Whole saliva is a body fluid of very complex character and composition. It contains many proteins of both glandular and nonglandular origin. It is obvious that the chemical composition and characterization of these salivary proteins must be more fully understood if one is to adequately understand the physiology and chemical pathology of the oral cavity. Evidence does exist for the presence of salivary proteins in plaque matrix and their role in the formation of the enamel pellicle and plaque. Recent efforts in our laboratory have resulted in the isolation and partial characterization of a group of proline-rich proteins from human parotid saliva. These highly soluble proteins are of special interest because they display in many ways fascinating similarities to structural proteins, such as collagen, and seem to undergo severe changes upon their release into the oral cavity. One of the aims of this research proposal concerns the complete chemical characterization of these unusual proteins. In this endeavour, we will study the action of several proteolytic enzymes either singly or in combination. The physico-chemical characteristics of these proteins will also be determined employing techniques such as optical rotatory dispersion and circular dichroism. Attempts at producing antibodies against these proteins will be undertaken. If successful, these antibodies will be used to quantitate the content of these proteins in oral fluids of both normal and diseased subjects. Our overall objective is, therefore, to fully understand the chemistry and structure of this unique group of proteins, which will enable us to conduct comparative studies with proteins of the connective tissue class and facilitate investigations aimed at the elucidation of their role in nature and certain oral diseases.